We propose to study the structure, synthesis and functions of bacterial membrane lipids along the following lines: (1) We shall continue studies on the mechanism for plasmalogen synthesis in anaerobic bacteria. This pathway is distinct from that found in higher organisms. (2) We shall continue to study the function of plasmalogens in bacterial membranes. These studies will focus on the physical properties of pure plasmalogens highly enriched with single cis or trans monounsaturated acyl and alk-1-enyl chains. We shall also use these plasmalogens in studies on membrane enzyme reconstitution. (3) We shall continue to study the connection between heptose deficiency in the core of E. coli lipopolysaccharide and the deficiency in major outer membrane proteins which we discovered. These studies will focus on the transcription and translation of the mRNA for these proteins. We shall institute a search for inhibitors of heptose biosynthesis or incorporation into lipopolysaccharide. (4) We shall study the potential protective effects of cyclopropane fatty acids in E. coli in the oxygen-dependent killing of these cells by phagocytes.